We have 2.5 week old chicks, and we only have the light on once a day at dusk, and only for half hour or so. BUT, they are in our laundry room, with the door closed. So, the heat stays in. Is there a way you can lift the light? Move it a little each day, and then start to take them outside for half hour or so when they get more feathers. It'll help them adjust. Trying to find my temp sheet.
Oh.... And when you do take them out, make sure that your chicks and your current flock are separated, yet close. They need to get used to each other before they join and get into the pecking order. (Yes, a lot of work).